The present invention relates to an absorbent article, such as a sanitary napkin, a panty liner or an incontinence protector, which is intended to be carried in the crotch region of the wearer inside the wearer""s panties or pants, said article having a generally elongated shape with two long sides, two short sides, two end-portions, a central portion located between the end-portions, a liquid-permeable casing sheet or top sheet which is intended to lie proximal to the wearer""s body in use, a liquid-impermeable casing sheet or backing sheet intended to lie distal from the wearer""s body in use, and between said sheets a drainage sheet and an element which forms a hump on the side of the article that lies proximal to the wearer""s body in use, as seen in a direction from the liquid-permeable casing sheet towards the liquid-impermeable casing sheet.
Conventional absorbent articles of the aforesaid kind are generally flat. Consequently, when the lower abdomen of the female carrier is not flat problems can occur when donning and wearing such articles. In such cases, abutment of the article with the wearer""s body is not of the best and if gaps occur between product and the user""s body there is a serious risk that body fluid will leak past the long side-edges of the article. Such leakage is particularly undesirable, since it is very liable to soil the wearer""s clothes. Rearward leakage is a particular problem in this respect, which normally occurs when the user lies down, for instance at night.
With the intention of solving this problem, it has been proposed to provide the absorbent articles with a pre-formed hump. Absorbent articles that include humps are described in EP-A-0 419 434, among others. The intention of providing absorbent articles with pre-formed humps is to create contact with the genitals of the wearer in use. Discharged body fluids can be caught immediately on leaving the wearer""s body and will be absorbed immediately by the article, without running out over its surface and over the long edges of the article.
Another drawback with flat articles is that when the article is used, it is influenced by forces exerted by the wearer""s thighs for instance, so as to wrinkle the product and/or cause the long edges of the product to fold over the liquid-permeable surface thereof. A wrinkled surface and/or inwardly folded long edges of the product will significantly reduce the liquid-permeable surface and in many cases to a size that is insufficient to capture all liquid discharged by the wearer at one time, wherewith leakage may occur.
A conventional way of creating a hump is simply to provide a large amount of absorbent material in the absorbent pad within the area where the hump is desired, and form the hump from this excess material. Humps are most often formed from an absorbent material referred to as cellulose fluff pulp, in other words defibred pulp from, e.g., thermomechanical pulp, chemithermomechanical pulp, or chemical sulphite pulp or sulphate pulp. Such a material, however, is not stable when wet, and consequently a hump comprised of such material will collapse and lose its shape when wet. In order to obtain a hump consisting of cellulose fluff pulp and having sufficient height whilst the article is in use, it is necessary to use so much cellulose fluff pulp in the production of the hump as to cause the hump to be felt uncomfortable by the wearer. Another problem that occurs with an article constructed in accordance with the above DESCRIPTION is that control of the liquid dispersion capacity of the article in the z-direction is lost, because the article loses its shape when wetted. It is also known to produce an article which includes a hump that faces towards the wearer, by placing a moulding or shaping element on top of the absorbent core. One drawback in this respect is that the hump results in inertia in liquid transportation down into the product, due to the fact that the shaping element must be filled with liquid before it releases the liquid to the underlying absorption core, said core having a strong liquid suction and absorbing effect and also a liquid retaining absorption effect. A hump can also be provided on the upper side of the article, by providing a planar article with a shaping element that takes a convex shape in relation to the wearer when the sides of the article in the region of the crotch are subjected to greater loads from the wearer""s thighs. The drawback with this solution is that the shaping element returns to its original planar state immediately the wearer does not subject the sides of the article to pressure, e.g. when she stands with her legs apart or sits in a xe2x80x9clotus positionxe2x80x9d, and also because it is difficult to produce a shape that corresponds essentially to the body shape of the wearer, solely by flexural deformation.
An absorbent article of the kind described in the introduction is known from EP-A1-0 768 072. However, in this case, the hump-forming element also constitutes the element that shall absorb and store discharged liquid and comprises a compressible, resilient and wet-stable material.
An object of the present invention is to provide an absorbent article of the aforesaid kind that conforms well to the wearer""s body, renders the risk of leakage but slight, and which allows a large volume of liquid discharged at one and the same time to be handled with only a slight risk of leakage.
These objects are achieved in accordance with the invention with an article of the kind described in the introduction that is characterised in that an absorption layer is disposed between the drainage layer and the hump-forming element, and in that the absorption layer and the drainage layer have a longitudinally extending cut along the longitudinal centre line of the article, where the underlying hump-forming element projects up through the absorption layer. Such a hump-forming element can be imparted highly effective liquid acquisition properties, meaning that a large volume of liquid delivered at one and the same time can be managed. The longitudinal cut in the absorption layer and the drainage layer also enables the material to be draped more easily around the hump-forming element, therewith enabling a pointed top on the hump to be obtained more readily.
In one preferred embodiment of the invention, at least that part of the hump-forming element that lies against the overlying absorption layer, i.e. the outer regions of the hump-forming material, is comprised of a material that has larger capillaries than the absorption layer and that preferably will present a somewhat retained shape in both a dry and a wet state, wherein that part of the hump-forming element that has been pushed up through the cut in the absorption layer and the drainage layer also has larger capillaries than the drainage layer. This results in an acquisition region that has an extra large capillary structure in the region of the cut up on the hump. A bordering absorption layer then drains the acquisition region and disperses the liquid within the absorption layer. This embodiment is particularly beneficial in those cases when a large volume of liquid is discharged over a short period of time.
The cut through the drainage layer and the absorption layer has a length of at least 20 mm, although preferably not greater than the length of the hump-forming element. In one beneficial variant, at least one of the end-portions of the longitudinally extending cut is joined to a further cut in the region of the end-portions of the longitudinally extending cut, these other angles defining between themselves and the imaginary extension of the longitudinal cut an angle xcex3 of between 10xc2x0-90xc2x0, said other cut having a length of between 3-25 mm, preferably between 5-15 mm.
The hump-forming element is preferably comprised of a pressure yieldable, preferably resilient material, that may be an absorbent or a non-absorbent material.
In a further embodiment of the invention, the density of the hump-forming element increases successively away from the absorption layer in a direction towards the liquid-impermeable casing sheet.
The absorption layer will conveniently extend outwardly of at least a part of the contour line of the hump-forming element, but inwardly of the contour line of the drainage sheet. The absorption layer is placed on top of a drainage layer, because rapid acquisition of liquid into the hump is desired, which contributes to a drier and more comfortable surface proximal to the wearer, and provides a softer, more comfortable hump.
The absorption layer may consist of a dry-formed sheet that contains 5-100% cellulose fibre and which has a density of between 100-300 g/m3, preferably between 200-250 g/m3 and a weight by surface area of between 30-2000 g/m2. The sheet will have been formed by compressing a web containing cellulose fibre in the absence of subsequent defibration and fluff forming, or by a compressed cellulose foam sheet that has a density of between 0.2-2.0 g/cm3.
The hump preferably has an elongate form and narrows in a direction towards the end-portions of the article and, when seen from one short side of the article, preferably has a triangular cross-section that has a greater width at the base than at the top and preferably a length of between 20 mm and 140 mm and a height between 5-20 mm. The hump may be disposed generally in the centre part of the article or the rear end-portion of the hump may extend into the rear end-portion of the article. The forward end-portion of the hump will preferably not extend into the region of the front end-portion of the article. In the case of such an embodiment, the hump will lie against the wearer""s crotch and will continue rearwards between the wearer""s buttocks so as to contribute towards an effective seal, primarily when the wearer lies down, for instance to sleep.